Segment frontend SentryJS errors by page path

We get a lot of errors that show up in Sentry as unique which are coming from the same page/view. While we will eventually have the source with sourcemaps enabled, being able to segment errors by the page path (already included via document.body.dataset.page), we'll have another view into errors.

Implementation

Add pagePath with value document.body.dataset.page to the Sentry init config.